A method of applying text with the aid of printing methods to cinematographic film where the language spoken on the film sound-track is different from the native tongue of the audience was devised more than fifty years ago. Normally, such text cannot be applied photographically, since only finished copies of the film are made available for export by the film company concerned, and not the negative. As evidenced by, for example, Norweigan Pat. Nos. 85 523; 93 143; 93 144; 94 660; 99 749 and 108 989, and Swedish Pat. Nos. 82,146; 84,499; 87,870; 92,700 and 334,538, such methods have long been known to the art. In present day methods the text is applied by covering the emulsion with a layer of wax which is brought into penetrating engagement with a printing block or plate provided with raised alphabetical letters, such as to expose the emulsion partially, whereafter the exposed emulsion is dissolved and removed and finally the wax is washed-off.
In known printing machines of the kind in question (e.g., Fr-A-2 239 708), the film is drawn forwards with the aid of a conventional feed arrangement, which includes a gripping mechanism, in a manner such that each frame of the film remains stationary for a given length of time in a printing station in which a printing block is pressed from beneath into engagement with the wax-coated layer of emulsion by means of a pressure plate which is coupled cinematographically with the gripping mechanism. A stationary counter-pressure plate is arranged in a bridge extending across the printing station. The pressure must be varied in accordance with the length of the text to be printed. For example, if the text "Help!" is printed with the same force as that applied when printing the words "my dear girl, you are wolfing your food", the film would be perforated as a result thereof. Consequently, the pressure plate is provided mechanically with a strong spring or a pneumatic device which can be adjusted to varying degrees of tension. In addition to making the machine complicated, it is difficult to achieve controllability for large and small pressure forces with one and the same spring. It should be possible to vary the counter-pressure within a range of, for example, 20-700 N. The operator has in front of him a manuscript on which he has noted the value of the counter-pressure required. When changing text, the operator operates a slide means, with which he permits a fresh printing block or plate to displace the preceding block from the printing station and to take its place. Known printing machines of this kind comprise in this order, a reel holder, a first wax-applicator for applying wax to the surface of the film frames, the printing machine, a second wax-applicator for applying wax to the perforated frame-edges (which cannot be waxed until the gripping machine has completed its function), an etching bath, a rinsing bath, a first drying section, two successive washing baths containing a wax-dissolving substance, a second drying station, and a winding-up device for winding-up the treated film. Although such prior art machines are constructed rationally for continuous operation, it still takes from five to six hours to provide a feature film with text, sub-titles, even when using the best apparatus known.